How auto captions work
The editor transcribes the speech in your video, splits it into words with their timings, and lays the words on the timeline as caption clips. Good tools let you correct a misheard word without breaking the timing, restyle all captions at once, and choose how many words appear at a time. For short vertical videos, two to four words per caption reads better than full subtitle lines.
Your options on a Mac
- Final Cut Pro can transcribe a clip to captions (added in Final Cut Pro 11). It is built for subtitles in long-form edits rather than animated social captions.
- CapCut's desktop app generates auto captions with animated templates and is free to start, with some features behind its own subscription.
- ClipForge generates captions on your Mac with word-highlight, pop-in and typewriter styles, plate, outline and shadow looks, and checks their contrast against the footage behind them.
Captions that sync to a voiceover you never recorded
If the voice is text-to-speech, there is no need to transcribe it at all. ClipForge times the captions from the speech engine's own word timings, so a synthetic voiceover and its captions match exactly, word for word. See text-to-speech voiceover on Mac.
Caption styles that read on a phone
- Word highlight: the current word changes colour. Easy to follow, the most common style on TikTok.
- Pop-in: each word appears as it is said. Energetic; good for hooks.
- Typewriter: letters appear in sequence. Good for a quieter, explanatory tone.
- Plate, outline or shadow: pick whichever keeps the text readable over bright and busy footage. A caption you cannot read is worse than none.
Where to put captions: the safe zone
Every vertical platform draws its own interface over your video: the username and caption text along the bottom, the like, comment and share buttons down the right side, and on some apps a header at the top. Captions placed there are partly hidden. Keep them in the middle band, slightly above centre, and away from the right edge.
The exact areas differ between TikTok, Reels, Shorts and feed placements, which is why ClipForge's export presets carry each network's safe zones and caption position: one master project, and each format gets captions where that app leaves them visible.
Step by step in ClipForge
- Import your clip, or build the video with a text-to-speech voiceover.
- Generate captions; transcription runs on your Mac.
- Read the captions through, then choose a style and a look that stays readable over your footage.
- Preview each platform format to see the captions inside its safe zone.
- Export to TikTok, Reels, Shorts, YouTube and feed formats from the same project.
Captions are part of ClipForge's free editor.
Questions
What are auto captions?
Captions generated automatically from a video's speech: the audio is transcribed and each word is placed on screen at the moment it is said. You then fix any misheard words and pick a style.
Can I make TikTok-style captions on a Mac?
Yes. Editors such as CapCut's desktop app and ClipForge generate captions and offer animated styles where the current word is highlighted. ClipForge transcribes on your Mac and places the captions inside each platform's safe zone.
Are on-device captions private?
On-device transcription runs on your Mac, so the audio does not need to be uploaded to a server to be captioned.
Where should captions go on a vertical video?
In the middle band of the frame. The bottom of a TikTok, Reels or Shorts video is covered by the caption text and buttons of the app itself, and the right edge by the like and share column, so captions placed there get hidden.